Merge branch 'main' into glitch-soc/merge-upstream

Conflicts:
- `app/lib/formatter.rb`:
  Upstream completely refactored the formatting code and removed that file,
  while glitch-soc had code for Markdown and HTML toots.
  Took upstream code, glitch-soc changes will be re-implemented on top of the
  refactored classes in a later commit.
- `app/models/status.rb`:
  Upstream refactored status edit handling and moved code to
  `app/models/concerns/status_snapshot_concern.rb`.
  Applied glitch-soc's changes to that file.
- `app/serializers/activitypub/note_serializer.rb`:
  Not really a conflict, just a line added too close to one modified by
  glitch-soc.
  Applied upstream changes while keeping the glitch-soc-modified one.
- `app/services/update_status_service.rb`:
  Not really a conflict, upstream modified a line adjacent to one added by
  glitch-soc.
  Applied upstream changes while keeping the glitch-soc line.
- `app/views/statuses/_simple_status.html.haml`:
  Upstream refactored formatting, glitch-soc changed the markup slightly.
  Applied upstream changes.
- `spec/lib/formatter_spec.rb`:
  Upstream completely refactored the formatting code and removed that file,
  while glitch-soc had code for Markdown and HTML toots.
  Took upstream code, glitch-soc changes will be re-implemented on top of the
  refactored classes in a later commit.

lib/mastodon/version.rb

@@ -17,7 +17,7 @@ module Mastodon
     end
 
     def flags
-      'rc1'
+      'rc3'
     end
 
     def suffix